TOMB OF THE UNKNOWNS

TOMB OF THE UNKNOWNS

KAREN BLEIER, AFPGetty Images

A US Army soldier, from the 3rd Infantry Regiment, walks his tour at the Tomb of the Unknowns at Arlington National Cemetery December 22, 2012 in Arlington, Virginia. The Army's 3rd Infantry Regiment, known as The Old Guard, has kept watch day and night over the site in Northern Virginia since 1948 without a moment's lapse.

A US Army soldier, from the 3rd Infantry Regiment, walks his tour at the Tomb of the Unknowns at Arlington National Cemetery December 22, 2012 in Arlington, Virginia. The Army's 3rd Infantry Regiment, known as The Old Guard, has kept watch day and night over the site in Northern Virginia since 1948 without a moment's lapse. (KAREN BLEIER, AFPGetty Images)

A US Army soldier, from the 3rd Infantry Regiment, walks his tour at the Tomb of the Unknowns at Arlington National Cemetery December 22, 2012 in Arlington, Virginia. The Army's 3rd Infantry Regiment, known as The Old Guard, has kept watch day and night over the site in Northern Virginia since 1948 without a moment's lapse.